US5670707A - Calibration method for a chromatography column - Google Patents
Calibration method for a chromatography column Download PDFInfo
- Publication number
- US5670707A US5670707A US08/743,450 US74345096A US5670707A US 5670707 A US5670707 A US 5670707A US 74345096 A US74345096 A US 74345096A US 5670707 A US5670707 A US 5670707A
- Authority
- US
- United States
- Prior art keywords
- column
- pressure
- temperature
- flow rate
- ratio
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/26—Conditioning of the fluid carrier; Flow patterns
- G01N30/28—Control of physical parameters of the fluid carrier
- G01N30/32—Control of physical parameters of the fluid carrier of pressure or speed
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N2030/022—Column chromatography characterised by the kind of separation mechanism
- G01N2030/025—Gas chromatography
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/26—Conditioning of the fluid carrier; Flow patterns
- G01N30/28—Control of physical parameters of the fluid carrier
- G01N30/32—Control of physical parameters of the fluid carrier of pressure or speed
- G01N2030/324—Control of physical parameters of the fluid carrier of pressure or speed speed, flow rate
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/88—Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86
- G01N2030/8804—Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86 automated systems
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N30/06—Preparation
- G01N30/10—Preparation using a splitter
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/26—Conditioning of the fluid carrier; Flow patterns
- G01N30/28—Control of physical parameters of the fluid carrier
- G01N30/30—Control of physical parameters of the fluid carrier of temperature
Definitions
- the present invention relates to chromatography and more particularly to a method of accurately determining characterizing parameters for chromatography columns and for improving chromatography repeatability.
- Chromatography is a method for separating chemical mixtures into their components.
- chromatographic analysis In chromatographic analysis an unknown mixture of chemicals is caused to flow into contact with a retentive media. The various portions of the mixture are detained by the media by differing amounts of time so that separations of the mixture are enabled.
- gas chromatography typically a supply of an inert gas called a carrier gas is continuously flowed through a device called a chromatography column.
- analytical chromatography the most common form of column is a very long hollow capillary tube. The interior walls of the capillary tube provide the retentive surface which interaction provides separation of the chemical components. Generally, the interior tube walls are chemically treated to enhance the separation.
- chromatographic column also includes tubes having packed particles providing a porous medium to detain the portions of a mixture.
- the primary separation mechanism in these columns is derived from the interactions between the surface of the particles and the flowing mixture.
- the mixture to be analyzed is loaded in liquid form into an injector where it is rapidly heated into the vapor state.
- the injector also provides a continuous flow of carrier gas into the column and when the sample unknown is vaporized it is introduced into the head of the column by the injector as a slug of gas.
- the slug is forced through the column by the pressure of the carrier gas and as the gases travel down the column, the components of the unknown sample separate into bands of like materials which like materials progress down the column at a common rate. Accordingly, at the output of the column, the various components leave the column in small bands separated in time.
- the time which the components travel through the column is a characteristic of the particular column, the column temperature, the carrier gas flow rate and the chemical of the component. Accordingly, a column can be calibrated so that the retention time of a chemical in the column is an unambiguous, qualitative identification of the chemical. Quantitative analysis of a sample is also enabled by determining the volumes of sample of the various bands and by integrating the signal of the detector at the exit of a column for each portion of the mixture.
- the most common prior art technique for calibrating a column involves performing a chromatography run using a reference chemical which is different from the carrier gas but which also has no chemical interaction with the column and measuring the retention time of the reference gas. From known formulas, the length and internal column diameter can then be calculated.
- this technique involves injection processes subject to mechanical and human error.
- these prior calibration processes are very time consuming and difficult to repeat exactly. Another source of error arises in the calculations because it is frequently assumed that the outlet pressure of the column is at atmospheric pressure. In fact, it is generally necessary to determine the exact pressure drop between the end of the column and the atmosphere because apparatus and fittings can cause significant back pressure which significantly effects the calibration.
- FIG. 1 is a schematic of the equipment configuration for column calibration.
- FIG. 2 is a schematic of the preferred flow diagram of the preferred calibration method.
- FIG. 3 is a schematic of the computerized flow controller employing the calibrated value of ##EQU4## ratio in the pressure control computer.
- FIG. 4 is a block diagram of the preferred chromatography control system.
- the column 6 is installed in a temperature controlled oven 5.
- the equipment necessary for determining the ratio further includes an electronic flow controller 1 under digital control from an operator input/output device 10 such as a key board.
- the electronic flow controller 1 is connected to receive the carrier gas from a pressure source.
- the carder gas should be the same as the carrier gas which is to be used in the tests with the chromatography column even though the calibration ratio ##EQU6## should be the same for different carrier gases.
- the flow controller 1 is connected via flow line 13 to an injector 2.
- the injector is preferably the same type, and even more preferably, the identical injector with which the column is to be used.
- Injectors are well known devices which are designed to receive a liquid sample to be analyzed which enable vaporization of the liquid sample and which ideally enable a slug of the vaporized sample to be introduced into the head of the column by the carrier gases and for the vaporized sample to be moved through the column by the flow of the carrier gas.
- the details of the injector are not a part of this invention but it is essential to appreciate that the injector employs a sample inlet port 17, comprising a septum (not shown) through which a syringe needle can be passed to deposit the liquid sample where it is vaporized.
- an injector 14 directs a potion of its inlet gas 13 into a septum purge vent 16.
- a pressure detector 3 is coupled to the purge outlet vent 16 or, alternatively, to the inlet 13.
- the pressure at the inlet 13 and outlets 16 and 18 are equal. Accordingly, pressure measured at the pressure detector 3 is equal to the pressure at the inlet to the column 6 except for a pressure drop in the tubing 19.
- the column 6 can be connected directedly to the injector 14 or if tubing 19 is employed it has a large diameter and is very short so that any pressure drop therein is negligible for the purposes of this application.
- the electronic flow controller 1 which is employed is pre-calibrated so that the output 41 of pressure meter 72, FIG. 3, is a measure of the flow from valve 70. Accordingly, valve 70 controls the flow from the supply 50 and valve 79 controls the head pressure at 13/15/51.
- a flow detector 8 can be used to measure the actual gas flow rate in the column 6 because all gas in the column flows through flow detector 8 and then to vent line 20.
- Tc column temperature (Kelvin)
- Ts standard temperature (Kelvin)
- step 21 the column to be calibrated is installed into the oven of the calibrating system.
- step 22 establish a first injector flow rate Q1 at a first column temperature TC1 and record the column head pressure P1 when the temperature TC1 is stable.
- step 24 establish a column head pressure P3, where P3>P1, and store/record flow rate Q3.
- the method of this invention for experimentally determining the ratio ##EQU21## is both more accurate and much faster than the prior art procedure of performing hold-up time measurements with non-retained chemicals.
- An additional advantage is that method of this invention can be fully automated, which will eliminate human error and permit re-calibration at set intervals.
- a further advantage of this technique is that if the column calibration is carried out using the same chromatography system which it is to be later used with the column that the process will automatically compensate for error between requested and established column oven temperatures during calibration. Since the calibration is performed using the temperatures measured and established by the chromatography system, any inaccuracy between actual column temperature and the column temperature reading will cause a corresponding change in the constant ##EQU22## Accordingly, subsequent use of the ##EQU23## ratio will tend to be correct for the temperature employed. Similarly, again assuming that the using system is the same as the calibration system, the value of ##EQU24## will also include a compensation for an error based on any back pressure differential between the column output and atmospheric pressure due to the presence of detectors and other devices restricting the output flow.
- FIG.3 a schematic of a typical computerized chromatography system is shown which system can be employed both for calibration of a column and to employ the column in many types of chromatography experiments.
- carrier gas enters the system 50 at relatively high pressure such as 40-100 psig at inlet 50 and then passes through a proportional control valve 70 and flow restrictor 73. As gas flows through the restrictor 73, it generates a pressure drop which is detected by sensor 72.
- An electronic control circuit 71 forms a closed loop controller by adjusting the drive voltage 40 to valve 70 in response to signal 41.
- the Central Processing Unit 80 provides control signal adjustment in response to a user's request 46 for a specified flow rate.
- the CPU 80 also continuously receives the column temperature information on bus 81 and accordingly, by using the known temperature 7 and pressure 42, the CPU is able to compute a temperature correction signal and pressure set point which is sent to the pressure controller 78.
- the pressure controller 78 adjusts the vent 79 to control the head pressure 51.
- Electronic flow controller 71 is corrected for maintaining desired mass flow rate by the computer 80.
- the calibration data for this compensation which relates pressure 51 and pressure signal 41 is stored in the memory of computer 80.
- FIG. 3 illustrates an injector 74 having a split mode and a splitless mode of operation.
- the three way diverting valve 76 is switched responsive to CPU control 44 so that gas can pass through the filter 77 and vent via proportional control valve 79.
- a pressure signal 42 is generated by pressure transducer 65 and represents the column head inlet pressure 51.
- Pressure controller 78 is responsive to pressure sensor 65, and to the CPU 80.
- the CPU performs the column flow equation computations to provide the pressure set point on bus 82 to the pressure controller 78.
- the pressure controller sends the control signal 43 to the proportional valve 79 and thereby controls the pressure at the column head and thereby the flow through the column 6.
- valve 76 In the splitless mode, the valve 76 is de-energized and the line 52 is directly connected to the proportional controller. Control of the injector pressure is still carried out in the same way by the pressure control computer 78.
- the split flow injector is used to split off a small portion of a sample for insertion of only a small slug of unknown sample for sweeping into the column by the carrier gas. Generally, after injection, the splitter is de-energized and the injector flow rate is reduced to save carrier gas.
- the CPU 80 is programmed and set up to solve the Poiseville equation 1! responsive to the User Entered Data 46, the viscosity equation 95 for the given gas and the ##EQU25## parameter 94. Based on the above data, the CPU calculates and stores a pressure set profile in memory 100 and a temperature set profile in memory 101 for the run. As a function of time, the appropriate set points 97 and 98 for pressure and temperature respectively are output from the CPU to their respective pressure and temperature controllers 93 and 92. The controllers employ electronic feedback controls to establish the requested set points and also feedback the actual measured values of actual column inlet pressure 36 and actual oven measured temperature 92 to the CPU.
- column flow rate could also be established by selecting viscosity data from a table for specific gases and temperatures and performing the set point column head pressure on the fly. Either approach requires an accurately calibrated ##EQU26## ratio in order to achieve repeatable results based on Poiseville equation computations.
Abstract
Description
let dQ=change in flow rate between temperature 1 and temperature 2 forconstant input pressure 5!
Q2=Q1-dQ
Claims (12)
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/743,450 US5670707A (en) | 1996-11-01 | 1996-11-01 | Calibration method for a chromatography column |
EP97107545A EP0840116B1 (en) | 1996-11-01 | 1997-05-07 | Calibration method for a chromatography column |
DE69731593T DE69731593T2 (en) | 1996-11-01 | 1997-05-07 | Calibration method for a chromatography column |
JP28764097A JP3775541B2 (en) | 1996-11-01 | 1997-10-06 | Calibration method for chromatography columns |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/743,450 US5670707A (en) | 1996-11-01 | 1996-11-01 | Calibration method for a chromatography column |
Publications (1)
Publication Number | Publication Date |
---|---|
US5670707A true US5670707A (en) | 1997-09-23 |
Family
ID=24988824
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US08/743,450 Expired - Lifetime US5670707A (en) | 1996-11-01 | 1996-11-01 | Calibration method for a chromatography column |
Country Status (4)
Country | Link |
---|---|
US (1) | US5670707A (en) |
EP (1) | EP0840116B1 (en) |
JP (1) | JP3775541B2 (en) |
DE (1) | DE69731593T2 (en) |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1041382A2 (en) * | 1999-02-25 | 2000-10-04 | THERMOQUEST ITALIA S.p.A. | Method and equipment for the realignment of peaks in gas chromatographic analyses |
US20020189947A1 (en) * | 2001-06-13 | 2002-12-19 | Eksigent Technologies Llp | Electroosmotic flow controller |
US20030052007A1 (en) * | 2001-06-13 | 2003-03-20 | Paul Phillip H. | Precision flow control system |
US20040238040A1 (en) * | 2003-05-28 | 2004-12-02 | Shimadzu Corporation | Gas chromatograph |
US20060016245A1 (en) * | 2004-07-26 | 2006-01-26 | Perkinelmer Las, Inc. | System for regulating fluid flowing through chromatographic column |
EP1925935A1 (en) * | 2006-11-23 | 2008-05-28 | Varian B.V. | Gas detection system and method |
US20080141758A1 (en) * | 2006-12-15 | 2008-06-19 | Thompson Michael Q | Pneumatic Testing For Gas Chromatograph Inlet |
EP2581741A1 (en) * | 2011-10-12 | 2013-04-17 | Agilent Technologies, Inc. | Method transfer by freezing an initially non-controlled parameter |
US9513267B1 (en) * | 2013-03-21 | 2016-12-06 | Mocon, Inc. | Reactor for near absolute conversion of alternative moiety-containing species into a select moiety-containing species and analytical instrument employing the reactor |
US20170153211A1 (en) * | 2015-12-01 | 2017-06-01 | Iball Instruments Llc | Mudlogging injection system |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE50111054D1 (en) * | 2001-12-21 | 2006-11-02 | Agilent Technologies Inc | Method of providing volumetric flows of fluids |
ITMI20022605A1 (en) | 2002-12-09 | 2004-06-10 | Thermo Finnigan Italia S P A | METHOD AND EQUIPMENT TO KEEP RETENTION TIMES CONSTANT IN GAS CHROMATOGRAPHIC ANALYSIS. |
JP4861121B2 (en) * | 2006-10-19 | 2012-01-25 | 富士通株式会社 | Hollow needle inspection device, hollow needle inspection method, and microinjection system |
JP2008267957A (en) * | 2007-04-19 | 2008-11-06 | Shimadzu Corp | Gas chromatograph, gas chromatograph/mass spectrometer, and column length measuring method |
WO2022239652A1 (en) * | 2021-05-13 | 2022-11-17 | 株式会社日立ハイテク | Method for adjusting pressure sensor, and liquid chromatograph analysis device |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5339673A (en) * | 1992-04-06 | 1994-08-23 | Shimadzu Corporation | Gas chromatograph and method of using same |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4994096A (en) * | 1989-05-09 | 1991-02-19 | Hewlett-Packard Co. | Gas chromatograph having integrated pressure programmer |
DE69323645T2 (en) * | 1992-05-18 | 1999-09-09 | Hewlett Packard Co | Procedure for calculating the operating parameters of a gas chromatograph |
IT1274775B (en) * | 1994-09-16 | 1997-07-24 | Fisons Instr Spa | METHOD AND DEVICE FOR THE CONTROL OF THE FLOW RATE OF CARRIER GAS IN GAS CHROMATOGRAPHIC APPLIANCES |
US5467635A (en) * | 1994-12-12 | 1995-11-21 | Shimadzu Corporation | Gas chromatograph |
-
1996
- 1996-11-01 US US08/743,450 patent/US5670707A/en not_active Expired - Lifetime
-
1997
- 1997-05-07 DE DE69731593T patent/DE69731593T2/en not_active Expired - Fee Related
- 1997-05-07 EP EP97107545A patent/EP0840116B1/en not_active Expired - Lifetime
- 1997-10-06 JP JP28764097A patent/JP3775541B2/en not_active Expired - Fee Related
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5339673A (en) * | 1992-04-06 | 1994-08-23 | Shimadzu Corporation | Gas chromatograph and method of using same |
Cited By (27)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1041382A3 (en) * | 1999-02-25 | 2004-07-21 | Thermo Finnigan Italia S.p.A. | Method and equipment for the realignment of peaks in gas chromatographic analyses |
EP1041382A2 (en) * | 1999-02-25 | 2000-10-04 | THERMOQUEST ITALIA S.p.A. | Method and equipment for the realignment of peaks in gas chromatographic analyses |
US20110186157A1 (en) * | 2001-06-13 | 2011-08-04 | Paul Phillip H | Precision Flow Control System |
US7465382B2 (en) | 2001-06-13 | 2008-12-16 | Eksigent Technologies Llc | Precision flow control system |
US20020195344A1 (en) * | 2001-06-13 | 2002-12-26 | Neyer David W. | Combined electroosmotic and pressure driven flow system |
US20040163957A1 (en) * | 2001-06-13 | 2004-08-26 | Neyer David W. | Flow control systems |
US20030052007A1 (en) * | 2001-06-13 | 2003-03-20 | Paul Phillip H. | Precision flow control system |
US7695603B2 (en) | 2001-06-13 | 2010-04-13 | Eksigent Technologies, Llc | Electroosmotic flow controller |
US7597790B2 (en) | 2001-06-13 | 2009-10-06 | Eksigent Technologies, Llc | Flow control systems |
US7927477B2 (en) | 2001-06-13 | 2011-04-19 | Ab Sciex Llc | Precision flow control system |
US8685218B2 (en) | 2001-06-13 | 2014-04-01 | Ab Sciex Llc | Precision flow control system |
US20090090174A1 (en) * | 2001-06-13 | 2009-04-09 | Paul Phillip H | Precision Flow Control System |
US20020189947A1 (en) * | 2001-06-13 | 2002-12-19 | Eksigent Technologies Llp | Electroosmotic flow controller |
US20040238040A1 (en) * | 2003-05-28 | 2004-12-02 | Shimadzu Corporation | Gas chromatograph |
US8297107B2 (en) | 2004-07-26 | 2012-10-30 | Perkinelmer Health Sciences, Inc. | System for regulating fluid flowing through chromatographic column |
US20070261474A1 (en) * | 2004-07-26 | 2007-11-15 | Andrew Tipler | System For Regulating Fluid Flowing Through Chromatographic Column |
US7219532B2 (en) * | 2004-07-26 | 2007-05-22 | Perkinelmer Las, Inc. | System for regulating fluid flowing through chromatographic column |
US20060016245A1 (en) * | 2004-07-26 | 2006-01-26 | Perkinelmer Las, Inc. | System for regulating fluid flowing through chromatographic column |
US7836750B2 (en) | 2006-11-23 | 2010-11-23 | Bruker Chemical Analysis, BV | Gas detection system and method |
US20080121015A1 (en) * | 2006-11-23 | 2008-05-29 | Varian, B.V. | Gas detection system and method |
EP1925935A1 (en) * | 2006-11-23 | 2008-05-28 | Varian B.V. | Gas detection system and method |
US7559227B2 (en) * | 2006-12-15 | 2009-07-14 | Agilent Technologies, Inc. | Pneumatic testing for gas chromatograph inlet |
US20080141758A1 (en) * | 2006-12-15 | 2008-06-19 | Thompson Michael Q | Pneumatic Testing For Gas Chromatograph Inlet |
EP2581741A1 (en) * | 2011-10-12 | 2013-04-17 | Agilent Technologies, Inc. | Method transfer by freezing an initially non-controlled parameter |
US9513267B1 (en) * | 2013-03-21 | 2016-12-06 | Mocon, Inc. | Reactor for near absolute conversion of alternative moiety-containing species into a select moiety-containing species and analytical instrument employing the reactor |
US20170153211A1 (en) * | 2015-12-01 | 2017-06-01 | Iball Instruments Llc | Mudlogging injection system |
US10132163B2 (en) * | 2015-12-01 | 2018-11-20 | Iball Instruments, Llc | Mudlogging injection system |
Also Published As
Publication number | Publication date |
---|---|
EP0840116A1 (en) | 1998-05-06 |
JPH10148631A (en) | 1998-06-02 |
JP3775541B2 (en) | 2006-05-17 |
DE69731593D1 (en) | 2004-12-23 |
EP0840116B1 (en) | 2004-11-17 |
DE69731593T2 (en) | 2005-11-10 |
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